Over 30 million people are infected with HIV worldwide, and 2.5 to 3 million new infections have been estimated to occur yearly. Although effective antiretroviral therapies are available, millions succumb to AIDS every year, especially in sub-Saharan Africa, underscoring the need to develop measures to prevent the spread of this disease.
An enveloped virus, HIV-1 hides from humoral recognition behind a wide array of protective mechanisms. The major envelope protein of HIV-1 is a glycoprotein of approximately 160 kD (gp160). During infection proteases of the host cell cleave gp160 into gp120 and gp41. gp41 is an integral membrane protein, while gp120 protrudes from the mature virus. Together gp120 and gp41 make up the HIV envelope spike, which is a target for neutralizing antibodies. Further, HIV envelope binds to CD4 and CC chemokine receptor 5 (CCR5) as co-receptors required for cellular entry and infection.
It is believed that immunization with an effective immunogen based on the HIV-1 envelope glycoprotein can elicit a neutralizing response, which may be protective against HIV infection. Further, it is believed that peptide therapeutics based on gp120 can neutralize gp120, and thus HIV. However, despite extensive effort, a need remains for immunogens and peptide therapeutics capable of such action.